An adjustable clamp is a tool which is used, for example, to draw two surfaces together in a clamping action. Also, adjustable clamps can be used to hold surfaces away from each other.
A particular problem is encountered when trying to clamp together two flat surfaces, end to end.
The problem can be appreciated from FIG. 1 where objects A and B are to be clamped together end to end. (The gap between objects A and B is exaggerated in FIG. 1 for clarity, but the intention is for the two objects to be clamped against each other end to end).
It would be impractical to use a standard clamp, of the type which seeks to compress items positioned between its jaws. For instance in FIG. 1, it would be impractical to position a standard clamp around the end points A′ and B′, since, in practice, objects A and B are likely to be very long. Moreover, if a standard clamp were to be placed over the end points A′ B′, a likely result when the clamping portions are brought together is that objects A and B may be forced out of linear alignment.
A known approach for clamping thin objects together end to end involves creating cut-out portions in the objects, and using clamps to pull the cut-out portions together. An example of a known cut-out arrangement is shown in FIG. 2a (although the clamp 10 shown in FIG. 2a is not known in the prior art, and is an exemplary embodiment of the present invention).
In FIG. 2a, the cut-out arrangement includes cut-away portions A″ B″ made in objects A and B respectively. In addition, a further cut-out portion C″ joins the two cut-away portions A″, B″, so that a clamp mechanism can be inserted into the combined cut-away portion A″, B″, C″.
The problem remains, however, that it is very difficult to manipulate known clamps in cut-away portions such as the one designated as A″, B″, C″ in FIG. 2.
A reason for the difficulty is that, in use, this form of clamping needs to be implemented sometimes on the undersurfaces of benches or tables, which exacerbates the problem of the user having to manipulate the clamp in such a confined area.
Prior art clamps have typically been manipulated using spanners or by turning a small lever arm, which requires the spanner or lever arm to be swept through an arc. In FIG. 2a, when a known clamp resides in the cut-out portion A″, B″, C″, it would be difficult to sweep the spanner or lever arm through the arc, because the walls and surface of the objects A, B tend to obstruct the sweep of the arc. At best, it is necessary to manipulate the spanner in very small increments, because the walls of the cut-out portion A″, B″, C″ limit the sweep of the arc.
Hence, it is difficult to use a spanner to rotate the appropriate part of a prior art clamp, because the surfaces of the objects A, B hinder access of the spanner to the known clamp residing in the cut-out portion A″, B″, C″.
The problem is made is made more difficult when having to use a spanner to manipulate the clamps in awkward locations such as the undersurfaces of tabletops and benches, and within cupboards or cabinets.
One clamp known the prior art which attempts to overcome the above disadvantages is described in WO 03/035992. This prior art clamp provides a first beveled gear member at one end of the clamp mechanism. A special tool is then provided which engages with a pivot locator positioned in a clamp member located adjacent to the end of the clamp mechanism including the first beveled gear member. The tool includes a second beveled gear member that engages with the first beveled gear member, such that the clamp may be operated by a rotation of the tool about its axis, which lies perpendicular to the axis of the clamp mechanism. Accordingly, the clamp may be operated without the necessity to sweep a spanner or lever through an arc that is obstructed by the walls and surfaces of the objects A, B.
However, there remain a number of disadvantages of the clamp disclosed in WO 03/035992. First, the clamp requires a special tool for its operation. This is a particular disadvantage for tradespersons, who are among the main users of these types of clamps, because the clamp tool must be stored, carried and kept on hand along with other tools of the trade. The clamp tool may easily be misplaced, lost, or simply not be within reach at the moment it is required. It is accordingly preferable that the clamp may be operated using a general purpose tool, such as a screwdriver or similar, that the tradesperson will always require and have on hand in the course of work.
Furthermore, space constraints limit the gear ratio achievable between the first gear member located on the clamp mechanism, and the second gear member located on the clamp tool. Accordingly, the torque delivered to the clamp mechanism is similar to the torque applied to the tool. In applications requiring high clamping force, it may be therefore be difficult to apply sufficient torque to the tool. In attempting to apply a high torque, the tool may easily slip from the pivot locator, which may result in injury to the operator, and/or stripping of the beveled gears on the clamp mechanism and the tool.
Additionally, all prior art clamps require the operator to hold the clamping mechanism in place during the initial stages of adjustment, until the clamp engages the surfaces to be held together with sufficient force to retain the mechanism in place. This may be difficult to achieve in awkward spaces, in which the task could be simplified if the operator were able to free up the hand not required for operation of the clamp.
It is therefore an object of the present invention to overcome or at least mitigate one or more of the problems in the above prior art, or to provide an improved alternative.
It is to be noted that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein.